NFSD: Demote a WARN to a pr_warn()

The call trace doesn't add much value, but it sure is noisy.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4proc.c

@@ -630,9 +630,9 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	}
 
 	status = nfsd4_process_open2(rqstp, resfh, open);
-	WARN(status && open->op_created,
-	     "nfsd4_process_open2 failed to open newly-created file! status=%u\n",
-	     be32_to_cpu(status));
+	if (status && open->op_created)
+		pr_warn("nfsd4_process_open2 failed to open newly-created file: status=%u\n",
+			be32_to_cpu(status));
 	if (reclaim && !status)
 		nn->somebody_reclaimed = true;
 out: